This invention relates to the manufacture of abrasive products.
Abrasive compacts are used extensively in cutting, milling, grinding, drilling and other abrasive operations. The abrasive compacts consist of a mass of diamond or cubic boron nitride particles bonded into a coherent, polycrystalline hard conglomerate. The abrasive particle content of abrasive compacts is high and there is an extensive amount of direct particle-to-particle bonding. Abrasive compacts are made under elevated temperature and pressure conditions at which the abrasive particle, be it diamond or cubic boron nitride, is crystallographically stable.
Abrasive compacts tend to be brittle and in use they are frequently supported by being bonded to a cemented carbide substrate. Such supported abrasive compacts are known in the art as composite abrasive compacts. The composite abrasive compact may be used as such in the working surface of an abrasive tool.
Examples of composite abrasive compacts can be found described in U.S. Pat. Nos. 3,745,623, 3,767,371, 3,743,489 and 4,063,909.
Composite abrasive compacts are generally produced by placing the components, in powdered form, necessary to form an abrasive compact on a cemented carbide substrate. This unbonded assembly is placed in a reaction capsule which is then placed in the reaction zone of a conventional high pressure/high temperature apparatus. The contents of the reaction capsule are subjected to conditions of elevated temperature and pressure at which the abrasive particles are crystallographically stable.
Other effective cubic boron nitride abrasive bodies which do not contain as high an abrasive particle content as abrasive compacts are also known and used in the art. Such abrasive bodies generally comprise a sintered body containing 40 to 60 volume percent of cubic boron nitride particles uniformly dispersed in a continuous ceramic bonding matrix. These abrasive bodies are also made under temperature and pressure conditions at which the cubic boron nitride is crystallographically stable. U.S. Pat. No. 4,469,802 describes such a body.
European Patent Publication No. 0278703 published 17 Aug. 1988 describes and claims a method of making an abrasive body which comprises a layer of bonded ultra-hard abrasive particles bonded to a substrate, including the steps of providing the substrate, depositing a layer of the components necessary to form the layer of bonded ultra-hard abrasive particles, in particulate form, in an organic binder on a surface of the substrate, and subjecting the substrate and layer to conditions of elevated temperature and pressure at which the ultra-hard abrasive particle is crystallographically stable. The layer of particulate components may be deposited on the surface of the substrate by suspending the particulate components in a liquid containing the organic binder dispersed or dissolved therein, depositing the liquid suspension on the surface and removing the liquid from the suspension. The layer of bonded ultra-hard abrasive particles will typically be a diamond or cubic boron nitride abrasive compact.